David Cameron calls for 'patience' in tackling British jihadists who have travelled to Iraq and Syria intent on murder, as fears grew that they could kill a second US journalist

At the end of the video, Steven Sotloff, another US journalist, was forced to parade in front of the camera and threatened with death unless President Barack Obama calls off air strikes against the Islamic State in Iraq and the Levant

The hunt for the jihadist who beheaded an American journalist is underway, as sources identified him as the leader of a group of British fighters known as “The Beatles”.

MI5, Scotland Yard and the FBI are trying to identify James Foley’s killer, who is reportedly known as “John” and part of a gang of three men named after the pop group by their hostages because of their British accents.

Details about the jihadist’s possible identity came as David Cameron called for “patience” in tackling British extremists who have travelled to Iraq and Syria intent on murder, as fears grew that they could kill a second US journalist.

The Prime Minister broke off his holidayand said he was “deeply shocked” at the beheading of James Foley by a masked man with a British accent at an unknown location in the Middle East. A video of the killing was published online.

Stephen Sotloff has been identified as the second journalist in the James Foley beheading video

At the end of the video, Steven Sotloff, another US journalist, was forced to parade in front of the camera and threatened with death unless President Barack Obama calls off air strikes against the Islamic State in Iraq and the Levant (Isil).

Mr Sotloff’s parents urged Mr Obama to save their son “by any means necessary”, while Mr Foley’s family urged the US to “look deeply” and do more to “protect courageous Americans”.

Michael Foley, the journalist’s brother, said: “I hope they do more for Steven [Sotloff]. There’s more that could be done. The footprint’s been laid by some of the other nations.” Mr Obama said the US will “do what is necessary to ensure justice is done” after Mr Foley’s murder.

In other developments:

— MI5, Scotland Yard and the FBI were trying to identify the killer, who is reportedly known as “John” and is the leader of three British jihadists known to their hostages as “The Beatles” because of their British accents.

— Security services and experts were analysing the video for clues to the killer’s identity and location of the murder.

— Mr Obama said Isil will ultimately fail because it only wants to “destroy” and has “no place in the 21st century”.

— It emerged that the White House was aware of a threat to murder Mr Foley a week ago, after being contacted by the journalist’s Boston employer, the Global Post, after the outlet received an email from his captors

— Philip Hammond, the Foreign Secretary, said British soldiers could be posted in Iraq to help train Kurdish fighters to take on Isil.

'Poison'

Mr Cameron conceded it was “increasingly likely” that Mr Foley’s killer was British, as he warned against making a “knee-jerk” reaction in response to the crisis.

Britain and its allies face a “generational struggle” to bring the “poison” of Islamist extremism to an end, the Prime Minister said. He added that “what happens in far-flung places can cause us huge harm here, too”.

He confirmed that the Government was prepared to consider tougher counter-terrorism laws to stop Islamist extremists travelling to Iraq and Syria. The murder underlined growing international concerns that up to 500 British jihadists have travelled to Iraq and Syria to fight alongside Isil and are committing “terrible crimes and atrocities”.

Downing Street sources said the Prime Minister, who returned to London from Cornwall to chair a meeting about the crisis, had watched the video.

Mr Cameron said after the meeting: “This is deeply shocking. But we know that far too many British citizens have travelled to Iraq and travelled to Syria to take part in extremism and violence. And what we must do is redouble all our efforts to stop people from going.

“To take away the passports of those contemplating travel, to arrest and prosecute those who take part in this extremism and violence. To take extremist material off the internet and do everything we can to keep our people safe. And that is what this Government will do.”

'Act of murder'

Mr Cameron said it was clear that Mr Foley’s murder was “an act of murder without any justification”.

“This is not the time for knee-jerk reaction, it is time for what Britain always shows in these circumstances and that is resolve,” he added. “We have defeated terrorism, extremism, threats to our country before and we will defeat them again if we show that resolve, but also patience.”

It also emerged that the Government removed 23 British passports from UK residents over fears that they were preparing to travel to the Middle East to join Isil, while 46 Isil videos have been removed from the internet.

Mr Obama said Mr Foley’s courage “stands in stark contrast to his killers”, who are a “cancer”.

“Today, the entire world was appalled by the murder of Jim Foley,” he said. “One thing we can all agree on is that Isil has no place in the 21st century. We share a common set of values rooted in the opposite of what we saw yesterday.

“We will continue to confront this hateful terrorism and replace it with a sense of hope and stability.

“That’s what Jim Foley stood for. A man who lived for his work, who courageously told the stories of his fellow human beings and who was liked and loved by friends and family.”

Analysts were last night trying to match the killer’s voice in the video to surveillance recordings of suspects. They were also using other clues, such as the man’s height and the fact that he is left-handed, to narrow their search.

Linguistic experts suggested the killer was from South London, possibly with some links to Afghanistan.

'Fearless'

Mr Foley’s parents, John and Diane, and his brother Michael, spoke to the media outside their home in New Hampshire, describing him as “the best of America”.

Mrs Foley said: “We’re very proud of him. He was a courageous, fearless journalist. He was just a hero.”

The family said their faith had been a comfort. John Foley said: “Jim is free. We know he’s in God’s hands. He’s in heaven. We’re so proud of him. None of it makes any sense.”

Mr Foley, 40, was seized in Idlib in northern Syria as he was travelling to the Turkish border in November 2012.

An experienced foreign correspondent, he had been kidnapped before, in Libya, but refused to give up the job.

He was kidnapped before Isil came into existence, suggesting the terror group bought him from his captors to use his death to generate propaganda.